Peroxy compounds are effective bleaching agents, and compositions including mono- or diperoxyacid compounds are useful for industrial or home laundering operations. For example, U.S. Pat. No. 3,996,152, issued Dec. 7, 1976, inventors Edwards et al., discloses bleaching compositions including peroxygen compounds such as diperazelaic acid and diperisophthalic acid.
However, granular bleaching products containing peroxyacid compounds tend to lose bleaching activity during storage, due to decomposition of the peroxyacid. The relative instability of peroxyacid presents a problem of storage stability for compositions consisting of or including peroxyacids.
One approach to the problem of reduced bleaching activity of peroxyacid compositions has been to include "activators" for, or precursors of, peroxyacids. U.S. Pat. No. 4,283,301, inventor Diehl, issued Aug. 11, 1981, discloses bleaching compositions including peroxygen bleaching compounds, such as sodium perborate monohydrate or sodium perborate tetrahydrate, and activator compounds such as isopropenyl hexanoate and hexanoyl malonic acid diethyl ester. However, these bleach activators tend to yield an unpleasant odor under actual wash conditions.
Another approach has been the use of cyanamides and nitriles which can react with alkaline hydrogen peroxide to form a peroxyimidic intermediate, which is a powerful oxidant. Thus, for example, Payne, Tetrahedron, 18, pp. 763-765 (1962) describes the reaction of benzonitrile and hydrogen peroxide to give an extremely reactive intermediate termed peroxybenzimidic acid. This intermediate is too reactive to be isolated, and actually will oxidize hydrogen peroxide itself to oxygen. Sawaki, Bull. Chem. Soc. Jpn., 54, pp. 793-799 (1981) summarized the reaction described by Payne, supra and also studied the effect of certain substituted benzonitriles (p-MeOPhCN, p-MePhCN, m-MePhCN, o-MePhCN, p-ClPhCN, and p-O.sub.2 NPhCN.
U.S. Pat. No. 4,756,845, issued Jul. 12, 1988, inventors Sugawara et al., discloses peroxide activators such as alkyl or alkoxy substituted dicyanobenzenes.
European patent application 91201170.7, published Nov. 27, 1991, inventor Oakes discloses peroxyacid bleach precursors that are prepared from an aromatic aldehyde or ketone by reaction with sodium cyanide and a dialkyl amine.
Furthermore, U.S. Pat. No. 4,199,466, issued Apr. 22, 1980, inventor Benson, discloses that certain cyanoamine compounds, such as N-cyanomonoalkylamines, N-cyanodialkylamines, N-cyanomonocycloalkylamines, N-cyanomonoheterocyclicamines, N-cyanoaralalkylamines, and N-cyano-N-(alkoxyaralkyl)amine, when employed under alkaline conditions act as activators of peroxide-based bleaches.
However, problems with the previously known cyanoamines, cyanamides, and nitriles activators have included limited stability, poor bleaching effectiveness, and low yields of active oxidizing intermediates.